residual energy ratio

Altair Forum User

hello,

 

When i perform an analysis in optistruct, the .out file gives a 'residual energy ratio' for every subcase. Is this the difference between the energy done by the forces and the strain energy? In other words, is a low value for the residual energy ratio an indication for a good model?

Rahul Rajan_21763

Hi,

Residual energy ratio with SPCFORCE. It is a measure of the error, the ratio between the work done by the unbalanced force and the work done by the external force (so it is a residual energy/strain energy).

 

If you request for SPCFORCE then in the *.out file 'Residual energy ratio' will be written in the out file. A value of 1.0e-08 or less is considered as acceptable. 

 

When you request SPCFORCE calculation you will get this information, below is an example: 

 

Residual energy ratio for static load case 1 = -1.583142E-13

--------------------------------------------------------------------------
Label x-force y-force z-force x-moment y-moment z-moment
--------------------------------------------------------------------------
Sum-App. 0.000E+00 -1.000E+03 0.000E+00 0.000E+00 0.000E+00 -6.000E+05
Sum-SPCF 0.000E+00 1.000E+03 0.000E+00 0.000E+00 0.000E+00 6.000E+05

 

Hence low value of Residual energy is good for model.

 

Regards

Rahul R